Distance values between a measuring device and an object can be measured by using optical methods without a physical contact between the device and the object. In these methods, the object is illuminated by the measuring device and the light is reflected back from the object and captured by a light detector of the measuring device.
Distance values can be determined for example by periodically modulating the intensity of the light which is emitted from the measuring device and by measuring a phase difference between the emitted light and the light reflected back and arriving at the detector. However, due to the periodicity of the light intensity, this method results in an ambiguous distance measurement.